This was some time ago. Absolutely awful interview process. My interviewer did not attend the first interview, at all, then when I asked my HR contact what had happened, it turns out the mail address is a chatbot! It said they would look into it then another recruiter (human) contacted me, apologized and interviewed me for a completely different role at another area. I went for it since I was looking for a job with relocation (note it was specifically written that they sponsored relocations for this opportunity).
This position had been open for 6+ months, opening and closing constantly. When I asked about it they said they did not have an immediate need and are waiting for the perfect person.
They stated a problem they currently have, and apparently have no solution. Then said "You are going to be hired to solve this problem, so, how would you solve it?"
I went on to explain, with references, that I solved this several times at other companies, but they were more interested in how they can solve it, with specific instructions.
I was really looking into relocating to their location so I gave in and gave detailed implementation details, for which all they said they "already tried it, didn't work so well" (although we were awarded a patent for this solution at another company, weird. When I asked how did they try a patented solution, they said they independently thought about it).
So in reality they were not hiring. They were looking for free consultation, and sadly they prey on people who applied for the possibility of relocation. Beware of that.